C++十进制转换成十六进制函数

Question

Write two overloaded functions that parse a decimal number into a hex number as a string. The function headers are as follows:

char * convertDecimalToHex(int value)
void convertDecimalToHex(int value, char *s)

Answer 1

#include<iostream.h>
#include<stdlib.h>
#define MAX 30
//main()的定义
int main(void)
{
char str[MAX],*p;

//从键盘上输入int数
cout<<"Please input a int:"<<endl;
int n;
cin>>n;

//将整型数n按十进制转换为字符串并输出
p=itoa(n,str,10);
cout<<"str="<<str<<endl;
cout<<"p="<<p<<endl;

//将整型数n按十六进制转换为字符串并输出
p=itoa(n,str,16);
cout<<"str="<<str<<endl;
cout<<"p="<<p<<endl;

//从键盘上输入double类型的数据
cout<<"Please input a double:"<<endl;
double x;
cout<<"x=";
cin>>x;

//将浮点数x转换为字符串后输出
p=gcvt(x,10,str);
cout<<"str="<<str<<endl;
cout<<"p="<<p<<endl;

return 0;
}

Answer 2

英语看不懂啊！！不过我知道十进制转换成16进制printf("%x\n",十进制数）；

Answer 3

#include<stdio.h>
char restr[50];
char * convertDecimalToHex(int value)
{
sprintf(restr,"%x",value);
return restr;
}
void convertDecimalToHex(int value, char *s)
{
sprintf(s,"%x",value);
}
void main()
{
int i=500;
printf("%s\n",convertDecimalToHex(i));
convertDecimalToHex(i, restr);
printf("%s\n",restr);
}

Answer 4

简便方法:
#include<stdio.h>

int main()
{
int n;
scanf("%d",&n);
printf("%X",n);
}
不简便方法:
#include<stdio.h>

int b[32],c=0;
int main()
{
int n,i;
scanf("%d",&n);
while(n>0)
{
b[c++]=n%16;
n/=16;
}
for(i=c-1;i>=0;i--)
if(b[i]<10) printf("%d",b[i]);
else printf("%c",b[i]-10+'A');
}